Scabies: Refine your exam, avoid these diagnostic pitfalls
Nearly half of all infections are missed when first examined. Attentiveness to specific details, particularly in 3 common scenarios, can help ensure an accurate Dx.
VIDEO shows scabies mite in motion
PRACTICE RECOMMENDATIONS
› Consider scabies with any severe pruritic eruption. Conduct a thorough physical exam, preferably with a dermatoscope, for burrows in the webs and sides of fingers, proximal palm, and wrists. A
› Consider scabies in all patients—especially the immunocompromised—who have distal white or yellow thick, scaly, or crusted plaques. C
› Include scabies in the differential when patients present with smooth nodules of the genitals or pruritic smooth papules and plaques in other locations. A
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Adjust treatment for special populations. Treatment of severe cases, such as crusted scabies, calls for combination therapy with oral ivermectin (200 mcg/kg) and 5% permethrin cream.26
Five percent permethrin cream is the preferred treatment for children weighing < 15 kg and pregnant women; oral ivermectin has not been studied for efficacy and safety in these populations.27
Effective response to treatment in these studies was measured by resolution of active scabies lesions and improvement in pruritus 1 to 2 weeks after treatment.
Anticipate these 3 clinical scenarios
The classic appearance of scabies usually triggers suspicion of its presence, leading to prompt identification of mite burrows and a correct diagnosis. Unfortunately, though, this is not always the case. And atypical presentations heighten the chance of diagnostic error, which overall occurs in nearly half of cases.1 Keep in mind the following common scenarios, to help improve diagnosis.
1. When a patient presents with a severe pruritic eruption, the clinician may be tempted to settle early on a form of dermatitis and not consider the possibility of scabies. When the patient is later seen by an expert, the burrows are easily identified. Solution: Whenever a patient complains of severe pruritus, use a dermatoscope to carefully examine the digits, web spaces, proximal palms, wrists, and ankles for burrows.
Continue to: A patient with distal white or yellow, thick, scaly, or crusted plaques
